Abstract: The projective synchronization of a class of master-slave chaotic system with unknown sector input nonlinearity,unknown uncertainty and external disturbance was discussed.By choosing an appropriate sliding mode surface,a sliding mode controller and adaptive update laws were designed to achieve synchronization based on the Lyapunov stability theory.The proposed controller has strong robust property since it is beyond the impact of unknown uncertainty and external disturbance.Simulation results of the uncertain master-slave Duffing-Holmes systems show the efficiency of the proposed controller.